So I just learned that the Mario Kart 64 PC Port already exists. It's called "Spaghetti Kart". There aren't any worthwhile mods for it yet, but the program adds a bunch of quality of life features such as disabling the rubber-banding AI and being able to play multiplayer without compromises (the original game would cut off music if played with 3 or more players).

I'm still of the camp who thinks that the game hasn't aged well, but this is much better than the vanilla N64 game. I bet it would be better when people start adding mods that replace the sprites with 3D models.

https://github.com/HarbourMasters/SpaghettiKart